Apparatus, system and method for radiation based imaging

ABSTRACT

A system and method relating to a radiation based imaging are provided. The system may include a radiation source, a detector and a first grid. The detector may include a plurality of detector cells. The first grid may be located between the radiation source and the detector cells and the first grid may include a plurality of radiation transmitting sections. At least one of the plurality of detector cells may include an active area which may be configured to receive radiation from the radiation source that passes through at least one of the plurality of radiation transmitting sections of the first grid. The active area may be adjustable by adjusting the first grid. The radiation source, the first grid and the detectors cells may be operatively coupled for detecting an object. The method may include adjusting the first grid to adjust the active area of the detector.

FIELD OF THE INVENTION

The present disclosure generally relates to a radiation based imagingsystem, and more particularly, to a grid for a detector and a radiationimaging system including such a detector.

BACKGROUND

A radiation detection or imaging system may be used in many fields suchas medical diagnosis and therapy, industrial production and application,scientific experiments and research, national security, etc. Generally,radiation detection or imaging may refer to a technology that may allownon-invasive observation of the interior of an object using radiation.As used herein, radiation may include a particle ray (for example,neutron, proton, electron, μ-meson, heavy ion, etc.), a photon ray (forexample, X-ray, γ-ray, α-ray, β-ray, ultraviolet, laser, etc.), or thelike, or any combination thereof. The information acquired by aradiation based imaging system may include, e.g., structure, density, orlesions, etc., without damaging the object. The term “object” as usedherein may include a substance, a tissue, an organ, a specimen, a body,or the like, or any combination thereof. The term “target” may be usedinterchangeably with the term “object.” For different objects to beimaged, different spatial resolutions may be needed. Thus, an apparatus,system, and method to adjust the spatial resolution are desired.

SUMMARY

In an aspect of the present disclosure, a system is provided. The systemmay include a radiation source, a detector, and a first grid. Theradiation source may be configured to generate radiation. The detectormay include a plurality of detector cells. The first grid may be locatedbetween the radiation source and the detector cells. The first grid mayinclude a plurality of radiation transmitting sections. At least one ofthe plurality of detector cells may include an active area which may beconfigured to receive radiation from the radiation source that passesthrough at least one of the plurality of radiation transmitting sectionsof the first grid. The active area may be adjustable by adjusting thefirst grid. The radiation source, the first grid and the detectors cellsmay be operatively coupled for detecting an object. As used herein,“coupled” or “operatively coupled” may indicate that one or morecomponents may work either alone or in combination cooperatively toachieve a function including, for example, detecting an object,adjusting a parameter of an imaging device or an image, etc.

In another aspect of the present disclosure, a method is provided. Themethod may include locating a first grid between a radiation source anda detector. The detector may include a plurality of detector cells andthe first grid may include a plurality of radiation transmittingsections. The method may further include emitting radiation from theradiation source toward the first grid and receiving, on an active areaof at least one of the plurality of detector cells, the radiation thatpasses through the first grid. The active area may be adjustable byadjusting the first grid. The radiation source, the first grid and thedetectors cells may be operatively coupled for detecting an object.

In some embodiments, the active area may be adjustable by adjusting theposition of the first grid. In some embodiments, the active area may beadjustable by tilting the first grid by an angle. In some embodiments,the angle may be any value between 0° to 360°.

In some embodiments, the system may further include a shielding devicewhich may be configured to adjustably block the radiation source. Insome embodiments, the configuration of the shielding device may be inthe form of a slip sheet, a shutter, a rotation blade, or the like, or acombination thereof.

In some embodiments, the system may further include a second grid. Thesecond grid may be located between the first grid and the detector. Insome embodiments, the first grid and the second grid may be moveablerelative to each other. In some embodiments, the first grid may beparallel to the second grid. In some embodiments, the first grid may bearranged at an angle to the second grid.

In some embodiments, the second grid may include a plurality ofradiation transmitting portions, and at least one of the plurality ofradiation transmitting portions may be coupled with an active area of adetector cell. In some embodiments, the extending direction of theradiation transmitting sections of the first grid and the extendingdirection of the radiation transmitting portions of the second grid maybe different.

In some embodiments, the active area of a detector cell may be at leastpartially determined by the at least one of the plurality of radiationtransmitting sections of the first grid and at least one of theplurality of radiation transmitting portions of the second grid.

In some embodiments, at least one of the plurality of radiationtransmitting sections may extend in a first direction. In someembodiments, the first grid may be moveable in a second directionperpendicular to the first direction. In some embodiments, the secondgrid may be moveable in the first direction. In some embodiments, thefirst direction may be parallel, or perpendicular to, or at an obliqueangle with the second direction. In some embodiments, the angle betweenthe first direction and the second direction may be any degrees, e.g.,10°, 15°, 20°, 25°, 30°, 40°, 45°, 60°, 75°, or the like.

In some embodiments, the radiation source may include a plurality offocal spots. The trajectory of the focal spot may be continuous ordiscrete. In some embodiments, the continuous trajectory may be a line,a sine curve, a sawtooth wave, or other regular or other irregularshape. In some embodiments, for the discrete trajectory, the number ofthe positions of the focal spot may be an arbitrary value, e.g., two,three, four, five. In some embodiments, the object may be scanned by theradiation form at least two different focal spots of the radiationsource.

Additional features will be set forth in part in the description whichfollows, and in part will become apparent to those skilled in the artupon examination of the following and the accompanying drawings or maybe learned by production or operation of the examples. The features ofthe present disclosure may be realized and attained by practice or useof various aspects of the methodologies, instrumentalities andcombinations set forth in the detailed examples discussed below.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is further described in terms of exemplaryembodiments. These exemplary embodiments are described in detail withreference to the drawings. These embodiments are non-limiting exemplaryembodiments, in which like reference numerals represent similarstructures throughout the several views of the drawings, and wherein:

FIG. 1 illustrates a block diagram of an X-ray imaging system accordingto some embodiments of the present disclosure;

FIG. 2 is a block diagram depicting an X-ray imaging system according tosome embodiments of the present disclosure;

FIG. 3 is a flowchart illustrating a process for X-ray imaging accordingto some embodiments of the present disclosure;

FIG. 4 is an exemplary schematic diagram of an X-ray imaging scanningsystem according to some embodiments of the present disclosure;

FIG. 5 is a flowchart of an exemplary process for X-ray scanningaccording to some embodiments of the present disclosure;

FIG. 6 is a 3D schematic of an X-ray imaging scanner according to someembodiments of the present disclosure;

FIG. 7 is a schematic sectional view of the effect of a flying focalspot on the active area of a detector cell according to some embodimentsof the present disclosure;

FIG. 8 is a schematic view of a detector array according to someembodiments of the present disclosure;

FIG. 9 is a schematic view of the active areas of detector cellsaccording to some embodiments of the present disclosure;

FIG. 10-A and FIG. 10-B are schematic diagrams showing an exemplaryarrangement of the grid and the detector cell according to someembodiments of the present disclosure;

FIG. 11-A and FIG. 11-B are schematic diagrams showing another exemplaryarrangement of the grid and the detector cell according to someembodiments of the present disclosure;

FIG. 12 is a schematic diagram showing another exemplary arrangement ofthe grid and the detector cell according to some embodiments of thepresent disclosure; and

FIG. 13-A and FIG. 13-B are schematic diagrams showing exemplaryarrangements of a grid, a shielding device, and detector cells accordingto some embodiments of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth by way of examples in order to provide a thorough understanding ofthe relevant disclosure. However, it should be apparent to those skilledin the art that the present disclosure may be practiced without suchdetails. In other instances, well known methods, procedures, systems,components, and/or circuitry have been described at a relativelyhigh-level, without detail, in order to avoid unnecessarily obscuringaspects of the present disclosure. Various modifications to thedisclosed embodiments will be readily apparent to those skilled in theart, and the general principles defined herein may be applied to otherembodiments and applications without departing from the spirits andscope of the present disclosure. Thus, the present disclosure is notlimited to the embodiments shown, but to be accorded the widest scopeconsistent with the claims.

It will be understood that the term “system,” “unit,” “module,” and/or“block” used herein are one method to distinguish different components,elements, parts, section or assembly of different level in ascendingorder. However, the terms may be displaced by other expression if theymay achieve the same purpose.

It will be understood that when a unit, module or block is referred toas being “on,” “connected to” or “coupled to” another unit, module, orblock, it may be directly on, connected or coupled to the other unit,module, or block, or intervening unit, module, or block may be present,unless the context clearly indicates otherwise. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

The terminology used herein is for the purposes of describing particularexamples and embodiments only, and is not intended to be limiting. Asused herein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “include,”and/or “comprise,” when used in this disclosure, specify the presence ofintegers, devices, behaviors, stated features, steps, elements,operations, and/or components, but do not exclude the presence oraddition of one or more other integers, devices, behaviors, features,steps, elements, operations, components, and/or groups thereof.

The present disclosure generally relates to a radiation based imagingsystem. Specifically, the disclosure provides a grid configured foradjusting an active area on a detector cell, and a radiation basedimaging system including a radiation source, a detector including aplurality of detector cells, and a grid including a plurality ofradiation transmitting sections. The grid may be adjusted so as toadjust an active area receiving radiation from the radiation source onthe detector cells. This may allow adjustment of the spatial resolutionof the imaging system such that the system may provide various spatialresolutions by adjusting, for example, the grid. The followingdescription is provided in the exemplary contexts of an X-ray imagingsystem or a CT scanner for illustration purposes, and not intended forlimiting the scope of the present disclosure. The system and methoddisclosed herein may be applicable to other radiation based imagingsystem. For brevity, a radiation based imaging system may be referred toas a system, or an imaging system in the present disclosure.

FIG. 1 illustrates a block diagram of the X-ray imaging system 100according to some embodiments of the present disclosure. As shown in thefigure, the X-ray imaging system 100 may include a gantry 101, an objecttable 102, a high voltage generator 103, an operational control computer104, an image generator 105, and an operator console and display 106.

The gantry 101 may be configured to house the components needed toproduce and detect X-rays to generate a CT image. The gantry 101 mayinclude an X-ray tube 108 and a detector 107. It should be noted that inalternative embodiments of the present disclosure, the high voltagegenerator 103 may be located in the gantry 201. The X-ray tube 108 maybe configured to emit radiation that may be received by the detector 107after it passes through an object exposed in the aperture of the gantry101. Merely by way of example, the radiation may include a particle ray,a photon ray, or the like, or any combination thereof. The particle raymay include neutron, proton, electron, μ-meson, heavy ion, or the like,or any combination thereof. The photon beam may include X-ray, γ-ray,α-ray, β-ray, ultraviolet, laser, or the like, or any combinationthereof. The object may include a substance, a tissue, an organ, anobject, a specimen, a body, or the like, or any combination thereof. Insome embodiments, the X-ray tube 108 may be a cold cathode ion tube, ahigh vacuum hot cathode tube, a rotating anode tube, etc. The shape ofthe X-ray beam emitted by the X-ray tube 108 may be a line, a narrowpencil, a narrow fan, a fan, a cone, a wedge, an irregular shape, or thelike, or any combination thereof. The shape of the detector 107 may beflat, arc-shaped, circular, or the like, or any combination thereof. Thefan angle of the arc-shaped detector may be an angle from 0° to 360°.The fan angle may be fixed or adjustable according to differentconditions including, for example, the desired resolution of an image,the size of an image, the sensitivity of a detector, the size ordistribution of detector cells on the detector, the stability of adetector, or the like, or any combination thereof. In some embodiments,the pixels of the detector 107 may be the number of the detector cells,e.g., the number of scintillator or photodetector, etc. The pixels ofthe detector may be arranged in a single row, two rows, or anothernumber of rows. The X-ray detector may be one-dimensional,two-dimensional, or three-dimensional.

The high voltage generator 103 may be configured to produce high voltageand/or current, and transmit it to the X-ray tube 108. The voltagegenerated by the high voltage generator 103 may range from 80 kV to 140kV, or from 120 kV to 140 kV. The current generated by the high voltagegenerator may range from 20 mA to 500 mA. In alternative embodiments ofthe present disclosure, the voltage generated by the high voltagegenerator 103 may range from 0 to 75 kV, or from 75 kV to 150 kV.

The operational control computer 104 may be configured to communicatebidirectionally with the gantry 101, the tube 108, the high voltagegenerator 103, the object table 102, the image generator 105, and/or theoperator console and display 106. Merely by way of example, the gantry101 may be controlled by the operational control computer 104 to rotateto a desired position that may be prescribed by a user via the operatorconsole and display 106. The operational control computer 104 may beconfigured to control the generation of the high voltage generator 103,for example, the magnitude of the voltage and/or the current generatedby the high voltage generator 103. As another example, the operationalcontrol computer 104 may be configured to control the display of imageson the operator console and display 106. For instance, the whole or partof an image may be displayed. In some embodiments, an image may bedivided into several sub-portions, which may be displayed on a screen atthe same time or in a certain order. According to some embodiments ofthe present disclosure, the user or the operator may select one or moresub-portions to display according to some conditions. Merely by way ofexample, the user may specify that an enlarged view of a sub-portion isto be displayed.

The operator console and display 106 may be coupled with the operationalcontrol computer 104 and the image generator 105. In some embodiments,the operator console and display 106 may be configured to display imagesgenerated by the image generator 105. In alternative embodiments, theoperator console and display 106 may be configured to send a command tothe image generator 105, and/or the operational control computer 104.Still in alternative embodiments of the present disclosure, the operatorconsole and display 106 may be configured to set parameters for a scan.The parameters may include acquisition parameters and/or reconstructionparameters. Merely by way of example, the acquisition parameters mayinclude tube potential, tube current, focal spots in the tube, reconparameters (e.g., slick thickness), scanning time, collimation/slicewidth, beam filtration, helical c, or the like, or any combinationthereof. The reconstruction parameters may include reconstruction fieldof view, reconstruction matrix, convolution kernel/reconstructionfilter, or the like, or any combination thereof.

The object table 102 may be configured to support a patient and movethough the aperture of the gantry 101 during an examination. As shown inFIG. 1, the direction of a patient being transmitted during anexamination is along the Z-direction. Depending on the ROI of thepatient selected or the protocols selected, the patient may bepositioned supine or prone, and either feet or head first. In someembodiments of the present disclosure, the object table 102 may beindexed between multiple scans. In some embodiments of the presentdisclosure, the object table 102 may be transmitted through the gantry101 at a constant speed. The speed may relate to the length of the areato be scanned, the total scanning time, the pitch selected, or the like,or any combination thereof. In some embodiments, the object table 102may be used to support an object other than a patient. Such a structuremay move the object for examination through the X-ray imaging system.For brevity, such a structure may also be referred to a patient.

It should be noted that the description of the X-ray imaging system isprovided for the purposes of illustration, and not intended to limit thescope of the present disclosure. For persons having ordinary skills inthe art, various variations and modifications may be conduct under theteaching of the present disclosure. However, those variations andmodifications may not depart from the protecting of the presentdisclosure. For example, the gantry 101 may further include amicrophone, sagittal laser alignment light, patient guide lights, X-rayexposure indicator light, energy stop buttons, gantry control panels,external laser alignment lights, etc.

FIG. 2 is a block diagram of an X-ray imaging system according to someembodiments of the present disclosure. It should be noted that X-rayimaging system described below is merely provided for illustrating anexample of the radiation imaging system, and not intended to limit thescope of the present disclosure. The radiation used herein may include aparticle ray, a photon ray, or the like, or any combination thereof. Theparticle ray may include neutron, proton, electron, μ-meson, heavy ion,or the like, or any combination thereof. The photon beam may includeX-ray, γ-ray, α-ray, β-ray, ultraviolet, laser, or the like, or anycombination thereof. For better understanding the present disclosure, anX-ray imaging system is described as an example of a radiation imagingsystem. The X-ray imaging system may find its applications in differentfields such as medicine or industry. In some embodiments of medicaldiagnosis, the X-ray imaging system may be a Computed Tomography (CT)system, a Digital Radiography (DR) system or may be used in some othermulti-modality system, e.g., a Computed Tomography-Positron EmissionTomography (CT-PET) system, a Computed Tomography-Magnetic ResonanceImaging (CT-MRI) system. In some embodiments of industrial application,the system may be used in internal inspection of components e.g., flawdetection, security scanning, failure analysis, metrology, assemblyanalysis, void analysis, wall thickness analysis, or the like, or anycombination thereof.

As illustrated in FIG. 2, an X-ray imaging system may include, an X-rayimaging scanner 210, a control module 220, a processing module 230, anda terminal 240. The X-ray imaging scanner may include an X-ray generatorand an X-ray detecting unit (see, for example, FIGS. 4 and 6). In someembodiments, the X-ray imaging scanner may include other componentsincluding, e.g., a gantry, a grid, a support table, etc. The controlmodule 220 may control the X-ray imaging scanner 210, the processingmodule 230, and/or the terminal 240. The processing module 230 mayprocess information received from the X-ray imaging scanner 210, thecontrol module 220, and/or the terminal 240, and generate one or more CTimages based on the information and deliver the images to the terminal240. The terminal 240 may be configured or used to receive input and/ordisplay output information.

The X-ray imaging scanner 210, the control module 220, the processingmodule 230, and the terminal 240 may be connected with each otherdirectly, or with an intermediate module (not shown in FIG. 2). Theintermediate module may be a visible component or an invisible field(radio, optical, sonic, electromagnetic induction, etc.). The connectionbetween different modules may be wired or wireless. The wired connectionmay include using a metal cable, an optical cable, a hybrid cable, aninterface, or the like, or any combination thereof. The wirelessconnection may include using a Local Area Network (LAN), a Wide AreaNetwork (WAN), a Bluetooth, a ZigBee, a Near Field Communication (NFC),or the like, or any combination thereof.

It should be noted that the above description about the radiation systemis merely an example. Obviously, to those skilled in the art, afterunderstanding the basic principles of the connection between differentmodules, the modules and connection between the modules may be modifiedor varied without departing from the principles. The modifications andvariations are still within the scope of the present disclosuredescribed above. In some embodiments, these modules may be independent,and in some embodiments, part of the modules may be integrated into onemodule to work together.

The X-ray imaging scanner 210 may be configured or used to scan anobject (not shown in FIG. 2) under examination and generate the sourcedata of an X-ray image. The object may be a substance, a tissue, anorgan, an object, a specimen, a body, or the like, or any combinationthereof. In some embodiments, the object may include a head, a breast, alung, a pleura, a mediastinum, an abdomen, a colon, a small intestine, abladder, a gallbladder, a triple warmer, a pelvic cavity, a backbone,extremities, a skeleton, a blood vessel, or the like, or any combinationthereof. The X-ray generating unit may be configured or used to generateX-rays to traverse the object under examination. The X-ray generatingunit may include an X-ray generator, a high-voltage tank, and/or one ormore other accessories. Additionally, the X-ray generator may includeone or more X-ray tubes which may emit X-rays by an X-ray tube.Moreover, the X-ray generating unit may be a cold cathode ion tube, ahigh vacuum hot cathode tube, a rotating anode tube, etc. The shape ofthe X-ray beam emitted may be a line, a narrow pencil, a narrow fan, afan, a cone, a wedge, or the like, or an irregular shape, or anycombination thereof. The X-ray tube in the X-ray generating unit may befixed at a point and it may translate or rotate in some scenarios. Insome embodiments, the focal spot of the X-ray beam may be in a fixedposition inside the X-ray generator. In some embodiments, the focal spotof the X-ray beam may be movable inside the X-ray generator, and thetrajectory of the focal spot may be continuous or discrete. In someembodiments, the continuous trajectory may be a line, a sine curve, asawtooth wave, or other regular or other irregular shape. In someembodiments, for the discrete trajectory, the number of the positions ofthe focal spot may be an arbitrary value, e.g., two, three, four, five.The positions may be in a line, in a plane or in a 3D space. In someembodiments, the interval between each two positions may be equivalentor not.

The X-ray detecting unit may be configured to receive the X-rays emittedfrom the X-ray generating unit or other radiation source. The X-raybeams from the X-ray generating unit may traverse the object underexamination. After receiving the X-rays, the X-ray detecting unit maygenerate the source data of an X-ray image of the object underexamination. The term “source data” may refer to the data that may bedetected by the X-ray detecting unit, and/or that may be transformed tothe image data according to an imaging processing procedure based on,for example, an algorithm. As used herein, the term “image data” mayrefer to the data that may be used to construct an image. The X-raydetecting unit may be configured to receive X-rays and generate thesource data of an X-ray image of the object under examination. The X-raydetecting unit may include an X-ray detector, and/or one or more othercomponents. The shape of the X-ray detector may be flat, arc-shaped,circular, or the like, or any combination thereof. The fan angle of anarc-shaped detector may be an angle from 0° to 360°. The fan angle maybe fixed or adjustable according to different conditions including, forexample, the desired resolution of an image, the size of an image, thesensitivity of a detector, the stability of a detector, or the like, orany combination thereof. In some embodiments, the X-ray detector may beone-dimensional, two-dimensional, or three-dimensional.

In some embodiments, there may be a collimator located or placed betweenthe X-ray generating unit and an object (or referred to as a target). Insome embodiments, there may be one or more grids between the target andthe detecting unit. The grids may be configured to absorb and/or blockthe scattered radiation from the object under examination. The number ofthe grids may be one, two, three, or any other value. In someembodiments, the grids may physically contact or be in direct contactwith each other. In some embodiments, the grids may be spaced apart fromeach other. In some embodiments, a grid and a detector may physicallycontact or be in direct contact with each other or be spaced apart fromeach other. In some embodiments, the grids may be parallel to adetector. In some embodiments, the grids may be placed at an angle tothe detector. The angle may be adjustable from 0° to 360°. In someembodiments, the grids may be parallel to one or more other grids. Insome embodiments, the grids may be placed with an adjustable angle from0° to 360° with each other.

It should be noted that the above description about the X-ray image unitis merely an example according to the present disclosure. Obviously, tothose skilled in the art, after understanding the basic principles ofthe X-ray image unit, the form and details of the X-ray image unit maybe modified or varied without departing from the principles. Themodifications and variations are still within the scope of the presentdisclosure described above.

The control module 220 may be configured to control the X-ray imagingscanner 210, the processing module 230, the terminal 240, or one or moreother units or devices in the system according to some embodiments ofthe present disclosure. The control module 220 may communicate with (byway of, for example, receiving information from and/or sendinginformation to) the X-ray imaging scanner 210, the processing module230, and/or the terminal 240. In some embodiments, the control module220 may provide a certain voltage, and/or certain current to the X-rayimaging scanner 210 for scanning. The voltage and/or current may bedifferent for different targets including, for example, people ofdifferent age, weight, height, etc.

In some embodiments, the control module 220 may control the position ofthe focal spot of an X-ray beam, the motion speed of the focal spot, theposition of one or more grids, or the like, or any combination thereof.See, for example, FIG. 4 and the description thereof. In someembodiments, the control module 220 may receive a command from theterminal 240 provided by, e.g., a user. Exemplary commands may include ascanning time, a location of the object to be examined, a rotating speedof the gantry, or the like, or any combination thereof. The controlmodule 220 may control the processing module 230 to select differentalgorithms to process the source data of an X-ray image.

The control module 220 may transmit a command to the terminal 240.Exemplary commands may include the size of an image, the location of animage, or the duration of an X-ray image to be displayed on a displayscreen. In some embodiments of the present disclosure, the X-ray imagemay be divided into several sub-portions for display, and the controlmodule 220 may control the number of the sub-portions.

It should be noted that the above description about the control unit ismerely an example according to the present disclosure. Obviously, tothose skilled in the art, after understanding the basic principles ofthe control unit, the form and details of the control module 220 may bemodified or varied without departing from the principles. Themodifications and variations are still within the scope of the presentdisclosure described above.

The terminal 240 may be configured or used to receive input and/ordisplay output information. The input and/or output information mayinclude programs, software, algorithms, data, text, number, images,voice, or the like, or any combination thereof. For example, a user oran operator may input an initial parameter or condition to initiate ascan. Exemplary parameters or conditions may include the scanning time,the location of the object for scanning, the rotating speed of thegantry, or the like, or a combination thereof. As another example, someinformation may be imported from an external source, such as a floppydisk, a hard disk, a USB flash drive, a wireless terminal, or the like,or any combination thereof. The terminal 240 may show the X-ray image ofan object from the processing module 230 to the user. The terminal 240may receive information from the control module 220 to adjust someparameters for displaying. Exemplary parameters may include the size ofan image, the location of an image, the time duration of an imageremains on a display screen, or the like, or a combination thereof. Theterminal 240 may display the whole or part of an X-ray image. In someembodiments, an X-ray image may be divided into several portions, whichmay be display on a screen at the same time or in a certain order. Insome embodiments of the present disclosure, the user or the operator mayselect one or more portions for display.

It should be noted that the above description about the display unit ismerely an example according to the present disclosure. Obviously, tothose skilled in the art, after understanding the basic principles ofthe display unit, the form and details of the display unit may bemodified or varied without departing from the principles. Themodifications and variations are still within the scope of the presentdisclosure described above.

It should be noted that the above description of the X-ray imagingsystem is merely provided for the purposes of illustration, and notintended to limit the scope of the present disclosure. For personshaving ordinary skills in the art, multiple variations and modificationsmay be made under the teachings of the present disclosure. For example,the assembly and/or function of the X-ray imaging system may be variedor changed according to specific implementation scenarios. Merely by wayof example, some other components may be added into the X-ray imagingsystem, such as a patient positioning unit, a high-voltage tank, anamplifier unit, a storage unit, an analog-to-digital converter, adigital-to-analog converter, an interface circuit, or the like, or anycombination thereof. Note that the X-ray imaging system may be atraditional or a single-modality system, or a multi-modality systemincluding, e.g., a Positron Emission Tomography-Computed Tomography(PET-CT) system, a Computed Tomography-Magnetic Resonance Imaging(CT-MRI) system, a remote medical X-ray imaging system, etc. However,those variations and modifications do not depart from the scope of thepresent disclosure.

FIG. 3 depicts a flowchart illustrating the process of an X-ray scanningaccording to some embodiments of the present disclosure. It should benoted that X-ray scanning process described below is merely provided forillustrating an example of the radiation imaging, and not intended tolimit the scope of the present disclosure.

As illustrated in FIG. 3, in step 301, X-ray beams may be generated.X-ray beams may be generated by the X-ray generating unit, or anotherradiation source. In some embodiments, an X-ray tube in the X-raygenerating unit may emit X-ray beams forming the shape of a line, anarrow pencil, a narrow fan, a fan, a cone, a wedge, or the like, or anirregular shape, or any combination thereof. The fan angle of the X-raybeams may be a certain value within the range from 0° to 360°. In someembodiments, before step 301, there may be some parameters to be set bya user or an operator. Exemplary parameters may include the parametersfor the gantry, for the X-ray tube, for the X-ray detector, for adisplay device, or for one or more other devices or units in orcommunicated with the system. Merely by way of example, a user may setparameters including a certain voltage, and/or a certain current forpeople of a certain age, weight, height, etc. In some embodiments, thegantry may be adjusted to a certain rotating speed according to someparameters. In some embodiments, the beam shape and the angle of a fanbeam may be selected based on one or more parameters. The type of theX-ray detector may be selectable based on one or more parameters. Itshould be noted that the above description about the parameters ismerely provided for the purposes of illustration, and not intended tolimit the scope of the present disclosure. For persons having ordinaryskills in the art, multiple variations and modifications about theparameters that are set may be made under the teachings of the presentdisclosure.

In step 302, the X-ray imaging scanner may be configured. In someembodiments, before scanning an object, noise in the system may bemeasured. In some embodiments, there may be one or more parameters to beadjusted according to a condition including, for example, a spatialresolution, sensitivity, stability, or the like, or any combinationthereof. Exemplary parameters may include the position of the focal spotof the X-ray beam, the motion speed of the focal spot, the position ofthe grids, or the like, or any combination thereof. In some embodiments,the spatial resolution may be adjusted or improved for a certain object(for example, a certain organ) than others. This may be achieved by, forexample, decreasing the area for receiving radiation in a pixel of anX-ray detector (e.g., a detector cell), referred to as an active area ofa pixel (for example, a detector cell). In some embodiments, the activearea may be adjusted by way of adjusting, for example, the position ofthe focal spot of the X-ray beam, the position(s) of the grid(s), thedistance of a grid from the X-ray source, the angle formed by a grid andan X-ray detector, the angle formed by two grids, the position of a gridrelative to another grid, or the like, or any combination thereof. Itshould be noted that the step 301 and step 302 described herein ismerely an example, and not intended to limit the scope of the presentdisclosure. For persons having ordinary skills in the art, multiplevariations and modifications in the form and structure may be made underthe teaching of the present disclosure. For example, the order of thesteps may be reversed, i.e., the X-ray imaging scanner may be configuredfirst, and the focal spot of the X-ray beam and the grids may beadjusted to the proper positions and then, the X-rays may be generated.

In step 303, the X-ray beams may be received by, for example, the X-raydetecting unit of the X-ray imaging scanner 210. In some embodiments,the X-ray detector of the X-ray detecting unit may receive X-ray beamsimpinging thereon. The impinging X-ray beams may include the X-ray beamsthat have traversed an object under examination, the X-ray beamsdirectly emitted from the X-ray generating unit, and/or the X-ray beamsfrom one or more other radiation sources. Parts of the X-ray beamsemitted from the X-ray generating unit may be blocked and/or absorbed byone or more grids located before the X-ray detector. In someembodiments, the X-ray beams may first be converted to light energy by,for example, a scintillator, and then an electrical signal may beproduced therefrom by, for example, a photodiode. The electrical signalmay be transmitted to, for example, the processing module 230.

It should be noted that the above description about the signalconversion is merely provided for the purposes of illustration, and notintended to limit the scope of the present disclosure. For personshaving ordinary skills in the art, multiple variations and modificationsin the form and structure may be made under the teaching of the presentdisclosure. For example, the scintillators may be replaced by othercomponents that may absorb the radiation and generate light energy, andthe photodiodes may be replaced by other components which may be capableof converting the light energy to electrical signals.

The received signals may be processed in step 304. In some embodiments,the processing module 230 may process the data from the X-ray detectorto generate the X-ray image data of an object under examination. Theprocess may involve an algorithm including, for example, a filtered backprojection, an n-PI, a tomosynthesis, or the like, or a combinationthereof. In this step, the image may be calibrated using a calibrationalgorithm. In some embodiments, the image data, the calibrated data,and/or the received signals from the processing module 230 may be storedin a storage unit and/or device. A storage unit or device may storeinformation by the way of electric, magnetic, or optical energy, etc.The device that store information by the way of electric energy mayinclude Random Access Memory (RAM), Read Only Memory (ROM), or the like,or any combination thereof. The device that stores information by theway of magnetic energy may include a hard disk, a floppy disk, amagnetic tape, a magnetic core memory, a bubble memory, a USB flashdrive, or the like, or any combination thereof. The device that storeinformation by the way of optical energy may include CD (Compact Disk),VCD (Video Compact Disk), or the like, or any combination thereof. Themethod to store information may include sequential storage, linkstorage, hash storage, index storage, or the like, or any combinationthereof.

The image data or the calibrated image may be shown to the user oroperator via the terminal 240. In some embodiments, the X-ray image ofthe object may be printed. In some embodiments, the calibrated oruncalibrated image data of the object may be transmitted to a thirdparty including, for example, a doctor. The doctor may make anassessment or decision based on the data received.

It should be noted that the above description about the process of X-rayscanning is merely an example according to the present disclosure.Obviously, to those skilled in the art, after understanding the basicprinciples of the process of X-ray scanning, the form and details of theprocess may be modified or varied without departing from the principles.In some embodiments, other steps may added in the process. For example,the results of the processing may be displayed on some devices, and theintermediated data and/or the final data of the process may be stored inthe process. The modifications and variations are still within the scopeof the present disclosure described above.

FIG. 4 is an exemplary schematic diagram of the CT scanning systemaccording to some embodiments of the present disclosure. As describedelsewhere in the disclosure, the control module 220 may be configured tocontrol the X-ray imaging scanner 210 in order to generate data forfurther processing by the processing module 230. During the operation ofthe scanning, different parts of the X-ray imaging scanner 210 may becontrolled separately by respective controllers. As shown in FIG. 4, thecontrol module 220 may include an X-ray controller 410, a gantrycontroller 420, and a grid controller 430.

The X-ray controller 410 may provide power and timing signals to anX-ray source 108. In some embodiments, the X-ray source 108 may includemore than one focal point, in which case the radiation received by thedetector 107 may come from different focal spots that a number of beampaths are produced during scanning. Thus, the one or more focal spotsgenerating the X-ray may be controlled by the X-ray controller 410 undercertain conditions in the scanning. During a scanning to acquire X-rayprojection data, the gantry and the components mounted thereon mayrotate about a center of rotation. The rotational speed and position ofthe gantry 101 may be controlled by the gantry controller 420. In thegantry, the X-ray source 108 may project an X-ray beam toward a detector107 or a collimator on the opposite side of the gantry.

In some embodiments, the detector 107 may be formed by a plurality ofdetector cells and a data acquisition system (not shown in FIG. 4). Theplurality of detector cells may sense the projected X-rays that passthrough a subject, and the data acquisition system may convert the datato digital or analog signals for subsequent processing. A detector cellmay produce a signal that may represent the intensity of an impingingX-ray beam. If an X-ray beam passes through the subject before reachingthe detector cell, the intensity of the impinging X-ray beam may beattenuated. In some embodiments, the working condition of a detectorcell may be controlled by the gantry controller 420. In someembodiments, the gantry controller 420 may control or adjust thesensitivity of a detector cell. For example, the gantry controller 420may be configured to adjust the detector cell(s) to provide a highersensitivity when scanning a structure/tissue of a small dimension. Inanother example, the sensitivity may be adjusted when the X-ray beam isblocked or partially blocked by, for example, a grid. As used herein,the sensitivity of a detector cell may represent the ability to detect aradiation signal with certain intensity. The sensitivity of a detectorcell may be related to, for example, the voltage applied on the detectorcell, the temperature of the detector cell, the material of the detectorcell, or the like, or a combination thereof.

One or more grids may be arranged or located between the X-ray source108 and the detector 107 in order to change the detection of radiationin some manner. In some embodiments, the grids may be controlled alongwith the detector 107. In some embodiments, one or more grids may becontrolled in relation with the focal points of the X-ray source 108.For instance, different focal spots may be applied along with differentgrid arrangements. The grid arrangement may be controlled by the gridcontroller 430. Exemplary grid arrangements may include changing thenumber of grids, selecting or replacing the types of grids, adjustingthe movement of one or more grids, or the like, or a combinationthereof. Changing the number of grids may include increasing ordecreasing grids used in the scanning. Considering that differentconfigurations of the grids may result in different scanning effect, thetype of the grids may be selected or replaced in some situations. Asused herein, the type of a grid may correspond or relate to thedimension of a radiation transmitting section, the shape of a radiationtransmitting section, the thickness of the grid, the material(s) of thegrid, or the like, or a combination thereof. A grid may include aplurality of radiation transmitting sections, or referred to asradiation transmitting portions. The dimension of radiation transmittingsections (or radiation transmitting sections) of a grid may affect thespatial resolution. As used herein, the radiation transmitting sectionor radiation transmitting portion may refer to the area on a grid thatradiation may not be absorbed or blocked. For instance, the radiationtransmitting section or radiation transmitting portion may be an openingor slit on the grid through which a radiation beam may pass throughwithout being absorbed or blocked. The radiation transmitting section orportion may have a shape of a circle, a square, a rectangle, or anyshape that is regular or irregular.

The dimension of the radiation transmitting sections may represent thewidth, length, radius, or area, of the radiation transmitting sections.The radiation transmitting section (or portion) may have acharacteristic dimension. As used herein, the characteristic dimensionof the radiation transmitting section (or portion) may be the smallestdimension of the radiation transmitting section (or portion) among itsdimensions including, for example, the length, the width, the radius,etc. Merely by way of example, for a circular radiation transmittingsection (or portion), the characteristic dimension is the radius of theradiation transmitting section (or portion). As another example, asquare radiation transmitting section (or portion), the characteristicdimension is the length of an edge of the radiation transmitting section(or portion). As a further example, a rectangular radiation transmittingsection (or portion), the characteristic dimension is the length of theshorter edge of the radiation transmitting section (or portion). Asstill a further example, for a radiation transmitting section (orportion) of an irregular shape, the characteristic dimension is thesmallest dimension among the one or more dimensions describing ordefining the shape of the radiation transmitting section (or portion).The characteristic dimension of a radiation transmitting section may beseveral orders higher than the wavelength of the radiation. Forinstance, the characteristic dimension of a transmitting section may beat least 10∧5 times, or at least 10∧6 times, or at least 10∧7 times, orat least 10∧8 times, or at least 10∧9 times, or at least 10∧10 times, orat least 10∧11 times of the wavelength of the radiation used in animaging system. The characteristic dimension of a radiation transmittingsection may be comparable to the dimension of a detector cell. Forinstance, assuming the dimension of a detector is 1 mm, thecharacteristic dimension of a radiation transmitting section may be 0.1mm, or 0.2 mm, or 0.3 mm, or 0.4 mm, or 0.5 mm, or 0.6 mm, or 0.8 mm.

The grid may include one or more radiation absorbing sections, orreferred to as radiation absorbing portions. As used herein, theradiation absorbing section or radiation absorbing portion may refer tothe area on a grid that radiation may be absorbed or blocked. Forinstance, radiation impinging on a radiation absorbing section orradiation absorbing portion may not pass through the grid.

In some embodiments, the radiation transmitting sections may be adjustedusing a shielding device. The shielding device may be coupled to thegrid. The shielding device may be a radiation blocker or absorber setin/on the grid, or coupled without contacting the grid. The shieldingdevice may be made of lead, gold, tungsten, depleted uranium, thorium,barium sulfate, tantalum, iridium, osmium, or the like, or anycombination thereof. The configuration of the shielding device may be inthe form of a slip sheet, a shutter, a rotation blade, or the like, or acombination thereof. Merely by way of example, a grid may include aplurality of radiation transmitting sections; a shielding device mayinclude multiple rotation blades; each of at least some of the radiationtransmitting sections may be associated with a rotation blade of theshielding device; the radiation transmitting sections of the grid withassociated rotation blades may be adjusted by rotating the rotationblades such that the areas of these radiation transmitting sectionsallowing the passage of radiation may be adjusted.

In some embodiments, the shielding device is not attached to or does nototherwise contact the grid. In some embodiments, a shielding device maybe movably attached to a grid. As used herein, a movable attachment mayindicate that the shielding device, or a portion thereof, may moverelative to the grid to which the shielding device attaches. Forinstance, a shielding device may include a plurality of shutters; theshutters may be movably attached to the grid.

The shielding device, or a portion thereof, may at least partially covera radiation transmitting section or portion. The coverage may beadjusted so that the open area of the radiation transmitting section orportion that may allow passage of radiation may be adjusted. Thecoverage may range from no coverage to full coverage. As indicatedherein, no coverage may indicate that the entire radiation transmittingsection or portion is available to allow passage of radiation. Asindicated herein, full coverage may indicate that the entire radiationtransmitting section or portion is covered by a shielding device or aportion thereof (for example, a shutter of the shielding device), andtherefore no portion of the radiation transmitting section or portion isavailable to allow passage of radiation.

The movement of a grid may lead to the movement of the radiationtransmitting sections on the grid. Merely by way of example, themovement of a grid may include a motion along a certain direction (e.g.,the Z-direction, or any direction on the x-y plane), a tilting withrespect to a certain axis, or the like, or a combination thereof. Themotion of the grid along a certain direction may cause the motion of theradiation transmitting sections on the grid, and the active area of adetector cell may also change. The tilting of a grid may also lead to achange of the active area of a detector cell. As used herein, the activearea of a detector cell may refer to the area that receives radiationtransmitted through the object and/or the grid(s) detectable by thedetector cell. In some embodiments, an active area of a detector cellmay relate to the spatial resolution of the imaging system. Forinstance, a small active area of a detector cell may correspond tohigher spatial resolution of the scanning system. In some embodiments,an active area of a detector may relate to the resolution of areconstructed image. For instance, the smaller active area of a detectormay correspond to higher resolution of a reconstructed image.

The X-ray controller 410, the gantry controller 420, and the gridcontroller 430 may be configured to operate systematically. Put anotherway, the operation of an X-ray source (e.g., the focal points), theoperation of the gantry (e.g., the rotation), and the arrangement of theone or more grids (e.g., the motion, the rotation) may be operativelycoupled with each other to provide, for example, a desired spatialresolution for subsequent processing. For example, the operation of anX-ray source, the operation of the gantry, and the arrangement of theone or more grids may be conducted in a coordinated way to achieve anadjustable spatial resolution. In some embodiments, one of the operationof an X-ray source, the operation of the gantry, and the arrangement ofthe one or more grids may be selectively conducted to change the spatialresolution.

Merely by way of example, a radiation-based imaging system may includetwo grids, a first grid and a second grid, a radiation source (forexample, an X-ray source), and a detector. The detector may include aplurality of detector cells. The two grids may be located between theradiation source and the detector. The spatial resolution of the systemmay be adjusted by adjusting the active areas of detector cells of thedetector. The adjustment may be achieved by adjusting a radiationtransmitting portion of one grid and/or a radiation transmitting sectionof the other grid to change the area that may allow radiation to passthrough. For a radiation beam to pass through both grids, the radiationbeam may need to pass through an area (referred to as an overlappingarea) where a radiation transmitting portion of one grid and/or aradiation transmitting section of the other grid overlap along the pathof the radiation beam. For instance, the adjustment may be achieved byadjusting the overlapping area by moving one or both grids, or tiltingone or both grids. Two or more way for adjustment may be combined.

As another example, the imaging system may include a grid. The spatialresolution of the system, or the active areas of detector cells of thedetector, may be adjusted by adjusting the area of a radiationtransmitting portion or section that may allow radiation to passthrough. For instance, the adjustment may be achieved by tilting a gridby an angle, or moving the position of the grid.

As a further example, the imaging system may include a shielding device.The shielding device may be configured to block at least part of theradiation from the radiation source. The spatial resolution of theimaging system may be adjusted by adjusting the shielding device. Theamount of the radiation blocked may be adjusted by adjusting theshielding device. In some embodiments, the shielding device may be aradiation blocker or absorber set in/on the grid, or coupled withoutcontacting the grid. The shielding device may be made of lead, gold,tungsten, depleted uranium, thorium, barium sulfate, tantalum, iridium,osmium, or the like, or any combination thereof. The configuration ofthe shielding device may be in the form of a slip sheet, a shutter, arotation blade, or the like, or a combination thereof. See relevantdescription regarding the shielding device elsewhere in the presentdisclosure.

One or more of the ways for adjusting the spatial resolution of theimaging system may be used alone, or in combination. For example, theadjustment of the position of the grid and the adjustment of theshielding device on the grid may be used cooperatively to achieve adesired spatial resolution.

It should be noted that the description of the CT scanning system isprovided for the purposes of illustration, and not intended to limit thescope of the present disclosure. For persons having ordinary skills inthe art, various variations and modifications may be conduct under theteaching of the present disclosure. However, those variations andmodifications may not depart from the protecting of the presentdisclosure. For example, the effect of the X-ray controller 410, thegantry controller 420, and/or the grid controller may be achieved by asingle integrated controller. Additionally, the controllers maycommunicate with each other through a wired connection, or thecommunication may also be realized in a wireless way.

FIG. 5 is an exemplary flowchart of an exemplary process for CT scanningaccording to some embodiments of the present disclosure. At step 501,the CT scanner may be initialized. During the initialization, aplurality of parameters may be set. Exemplary parameters to beinitialized may include, for example, the parameters relating to theX-ray source, the parameters relating to the detector, the parametersrelating to the detector cells, the parameters relating to the gantryand components mounted thereon, the parameters relating to the grids,the parameters relating to the reconstruction process, or the like, or acombination thereof. The parameters relating to the X-ray source mayinclude the shape of the X-ray beams including, for example, a line, anarrow pencil, a narrow fan, a cone, a wedge, an irregular shape, or thelike, or a combination thereof, emitted by the X-ray tube. In someembodiments, a plurality of focal spots may be configured to emit theX-rays in the X-ray source. The size and/or position of the focal spotsmay be initialized to for subsequent processing. The CT scanner may alsoinclude a shielding device configured to adjustably block the radiationfrom the X-ray source. The parameters relating to the detector mayinclude the shape of the detector including, e.g., flat, arc-shaped,circular, etc. The parameters relating to the detector cells may includethe size and/or the sensitivity of the cell. The parameters relating tothe gantry and components mounted thereon may include the rotationalspeed of the gantry. The parameters relating to the grids may includethe arrangement of the grids, such as, the number of the grids. Theparameters relating to the reconstruction process may include the shapeand/or size of voxels, the algorithm for calculating the values ofrespective voxels, the algorithm for reconstructing an image data (e.g.,iterative projection, filtered back projection, etc.), or the like, or acombination thereof.

A spatial resolution of the scanning system may be assessed at step 502.If a desired spatial resolution is satisfied, an object may be scannedin step 506. If the desired spatial resolution is not satisfied, one ormore parameters may be adjusted. Merely by way of example, in order toachieve higher spatial resolution in the scanning system, at step 503,the size and/or position of the focal spots may be adjusted, theshielding device, and/or the first grid and/or the second grid (ifapplicable) may be adjusted. The adjustment may be such that the amountand/or distribution of radiation impinging on detector cells of thedetector are changed to provide the desired spatial resolution. Theactive area of a detector cell may receive radiation from a radiationsource that passes through at least one of a plurality of radiationtransmitting sections or portions of a grid. See relevant descriptionelsewhere in the present disclosure. Various adjustments may be suchthat active areas of detector cells are changed to provide the desiredspatial resolution. For instance, if a grid is used, the adjustment maybe achieved by adjusting the area of a radiation transmitting portion orsection that may allow radiation to pass through. For instance, theadjustment may be achieved by tilting a grid by an angle, or moving theposition of the grid. If a plurality of grids are used, the adjustmentmay be achieved by adjusting a radiation transmitting portion of onegrid and/or a radiation transmitting section of the other grid to changethe area that may allow radiation to pass through. For a radiation beamto pass through both grids, the radiation beam may need to pass throughan area where a radiation transmitting portion of one grid and/or aradiation transmitting section of the other grid overlap along the pathof the radiation beam. For instance, the adjustment may be achieved byadjusting the overlapping area by moving one or both grids, or tiltingone or both grids. Two or more ways for adjustment may be combined. Forinstance, the adjustment of the shielding device may be combined withthe adjustment of one or more grids to achieve a desired spatialresolution.

Merely by way of example, two grids are included. The adjustment of thefirst and/or the second grids may include arranging the positions of thefirst grid and/or the second grid. For example, the first grid may bearranged to move along a first direction, and/or the second grid may bearranged to move along a second direction. The first direction may beparallel, or perpendicular to, or at an oblique angle with the seconddirection. For instance, the angle between the first direction and thesecond direction may be any degrees, e.g., 10°, 15°, 20°, 25°, 30°, 40°,45°, 60°, 75°, or the like. In another example, the first grid may bearranged to tilt about an axis by a certain angle, and/or the secondgrid may be arranged to move along a certain direction. In a furtherexample, the first grid may be arranged to tilt about an axis by a firstangle, and/or the second grid may be arranged to tilt about another axisby a second angle. As used herein, the first direction/angel may beeither the same as or different from the second direction/angel. In someembodiments, the extending direction of the radiation transmittingsections on the first grid and the second grid may be different. Forexample, the extending direction of the radiation transmitting sectionson the first grid may be perpendicular to the extending direction of theradiation transmitting sections on the second grid. In some embodiments,the term “radiation transmitting section” may be used in associationwith the first grid, and the term “radiation transmitting portion” maybe used in association with the second grid. In some embodiments, thefirst grid may be arranged to move along the direction perpendicular tothe extending direction of the radiation transmitting sections on thefirst grid (e.g., X-direction, or Y-direction), and the second grid maybe arranged to move along the direction perpendicular to the extendingdirection of the radiation transmitting sections on the second grid(e.g., Z-direction). In some embodiments, the adjustment of the focalpoint, the first grid, and the second grid may be operatively coupledwith each other. For example, the position of the focal spot may berepresented by function ƒ(x, y, z), the position of the first grid maybe represented by function ƒ₁(x₁, y₁, z₁), and the position of thesecond grid may be represented by function ƒ₂(x₂, y₂, z₂). Bycontrolling the position of the focal point, the position of the firstgrid, and the position of the second grid, the active area on arespective detector cell may be adjusted, which may result in a specificspatial resolution. The adjustment may be expressed as

Q(S,P)=Control[f(x,y,z),f ₁(x ₁ ,y ₁ ,z ₁),f ₂(x ₂ ,y ₂ ,z ₂)],  (1)

where Q(S, P) is the controlling process, Control is the controllingmethod. The detailed descriptions about the adjustment may be foundelsewhere in the present disclosure.

An object may be scanned at step 506. Another assessment may beconducted at step 507. If another adjustment is needed, parameters ofinterest, such as, the position of the focal points, the parametersrelating to the first and/or the second grid may be adjusted. If noadjustment is needed, image reconstruction may be performed at step 508.Merely by way of examples, a plurality of iterations may be performedduring the reconstruction, such that during each of the iterations, areconstructed image may be generated. When a termination criterion issatisfied, for example, the difference between the reconstructed imagefrom the current iteration and the preceding iteration is below acertain threshold, the iteration may terminate. A reconstructed imagemay be proceeded to perform image correction at step 509. During theimage correction, the noise in the reconstructed image may be furtherreduced. Moreover, step 508 may also include a process to enhance thecontrast of the reconstructed image.

It should be noted that the description of the scanning system isprovided for the purposes of illustration, and not intended to limit thescope of the present disclosure. For persons having ordinary skills inthe art, various variations and modifications may be conduct under theteaching of the present disclosure. However, those variations andmodifications may not depart from the protecting of the presentdisclosure. For example, the initialization may be performed byexecuting instructions stored in a storage unit, or a user may controlthe initialization and set the parameters manually. The workingcondition and/or sensitivity of detector cells may also be taken inaccount when the scanning system is initialized and/or the parameters ofinterest is adjusted.

FIG. 6 is a 3D schematic of an X-ray imaging scanner with two grids setbefore the X-ray detector. It should be noted that the configurationdescribed in the figure is merely for exemplary purposes, and is notintended to be limiting.

As shown in FIG. 6, an X-ray generating unit 601 may emit radiationtoward, for example, an object 602, a grid (for example, a first grid603, a second grid 604, etc.), an X-ray detector 605, or the like, or acombination thereof. The radiation traversing the object 602 may bedetected by the X-ray detector 605. Because of the first grid 603 andthe second grid 604 located between the object 602 and the X-raydetector 605, part of the radiation may be blocked and/or absorbed. Theshape of the X-ray beams emitted by the X-ray generating unit 601 may bea line, a narrow pencil, a narrow fan, a fan, a cone, a wedge, or thelike, or an irregular shape, or any combination thereof. The X-raygenerating unit 601 may include a focal spot where the radiation isemitted. In some embodiments, the focal spot of the radiation including,for example, X-ray beams, may be at a fixed position inside the X-raygenerator or the X-ray generating unit 601. In some embodiments, thefocal spot of the radiation including, for example, X-ray beams, may bemovable inside the X-ray generator or the X-ray generating unit 601. Thetrajectory of the focal spot may be continuous or discrete. In someembodiments, the continuous trajectory may be a line, a sine curve, asawtooth wave, or other regular or other irregular shape. In someembodiments, for the discrete trajectory, the number of the positions ofthe focal spot may be, for example, two, three, four, five, or more. Thepositions may be in a line, in a plane, or in a three-dimensional (3D)space. In some embodiments, the interval between each two positions maybe equivalent or not. In some embodiments, the shape formed by thesepositions may be a triangle, isosceles or not. In some embodiments, theshape formed by these positions may be a quadrangle, including, arectangle, a diamond, or any shapes with four edges. In someembodiments, the shape formed by these positions may be a circular, anellipse. In some other embodiments, the shape formed by these positionsmay be a three dimensional figure, including a solid, a sphere, or anyshapes regular or irregular. The speed and the movement of the focalspot may be controlled by the X-ray controller 410 according to thedemands including, the spatial resolution, the position of the grids setin the system, or the like, or a combination thereof. The X-raycontroller 410 may supply a control parameter to the X-ray generatingunit, including, a voltage, a current, an electric field, a magneticfield, or the like, or any combination thereof. In some embodiments, thecontrol parameter may be constant or variable. In some embodiments, thevariation may be continuous or a step change, and the step may be equalor unequal. With the movement of the focal spot of the X-ray beam, theactive area of receiving radiation for a detector cell of an X-raydetector may be changed. In some embodiments, the active area ofreceiving radiation for each detector cell may be changed. In someembodiments, the active area of receiving radiation for part of thedetector cells may be changed.

As shown in FIG. 6, the first grid 603 and the second grid 604 setbetween the target 602 and the X-ray detector 605 may be configured toblock and/or absorb some radiation traversing the target 602 and theradiations directly from the X-ray generating unit 601. It should benoted that the grids 603 and 604 are merely for exemplary purposes, andis not intended to be limiting. In some embodiments, there may be one ormore grids set between the target 602 and the X-ray detector 605. Insome embodiments, there may be one or more collimators (not shown inFIG. 6)) set between the X-ray generating unit 601 and the target 602.The shape of the grids may be flat, arc-shaped, circular, or the like,or any combination thereof, and the first grid 603 and the second grid604 may be the same or different in configuration. As illustrated inFIG. 6, the first grid 603 may include a plurality of radiationabsorbing portions 603-A and a plurality of radiation transmittingportions 603-B. The second grid 604 may include a plurality of radiationabsorbing portions 604-A and a plurality of radiation transmittingportions 604-B. The first grid 603 may be parallel to the second grid604. The radiation transmitting portions 603-B may be parallel with eachother, extending along the X-direction. The radiation transmittingportions 604-B may also be parallel with each other, extending along theZ-direction. As described elsewhere in the disclosure, at least oneshielding device may be used in combination with the first grid 603and/or the second grid 604 so as to adjustably block the radiation fromthe X-ray source. The shielding device may be arranged in differentmanners. For example, the shielding device may be placed between thedetector and the grid. For another example, the shielding device may beplaced between the detector and the second grid 604. For still anotherexample, the shielding device may be placed between the first grid 603and the second grid 604. In a further example, a plurality of shieldingdevices may be placed in different positions with respect to differentgrids. Embodiments of the shielding device are illustrated in FIG. 13-Aand FIG. 13-B and the description thereof.

It should be noted that the above description about the grids is merelyan example, and not intended to limit the scope of the presentdisclosure. For persons having ordinary skills in the art, multiplevariations and modifications may be made under the teachings of thepresent disclosure. For example, the shape of the radiation transmittingportions 603-B and/or the radiation transmitting portions 604-B may beregular or irregular. In some embodiments, the radiation transmittingportions 603-B and/or the radiation transmitting portions 604-B may beuniform in shape. In some other embodiments, a first part of theradiation transmitting portions 603-B and/or the radiation transmittingportions 604-B is same in shape, a second part of the radiationtransmitting portions 603-B and/or the radiation transmitting portions604-B is in a shape different from those of the first part. The widthand the length of the radiation transmitting portions 603-B and/or theradiation transmitting portions 604-B may be arbitrary. In someembodiments, the grid pitch of the radiation transmitting portions 603-Band the radiation transmitting portions 604-B may be the same ordifferent. For either grid, the pitches of the radiation transmittingportions may be uniform, or partially uniform, or non-uniform.

The radiation absorbing portions 603-A and/or 604-A may be formed withhighly absorbing material with large density or heavy nuclei atoms. Insome embodiments, the absorbing material of the radiation absorbingportions 603-A may be same with the material of the radiation absorbingportions 604-A. In some embodiments, the absorbing material of theradiation absorbing portions 603-A may be different from the material ofthe radiation absorbing portions 604-A. Merely by way of example, theabsorbing materials may be lead, gold, tungsten, depleted uranium,thorium, barium sulfate, tantalum, iridium, osmium, or the like, or anycombination thereof. The radiation transmitting portions 603-B and 604-Bmay include any material whose absorbability is smaller than theabsorbing materials. The radiation transmitting portions 603-B and 604-Bmay be filled with materials including gas, inorganic material, organicmaterial, or the like, or any combination thereof. For example, the gasmay include oxygen, nitrogen, carbon dioxide, hydrogen, air, or thelike, or any combination thereof. Exemplary inorganic material mayinclude silicon, carbon fiber, glass, etc. Exemplary organic materialmay include plastic, rubber, etc. In some embodiments, the material ofthe radiation transmitting portion 603-B may be same with the materialof the radiation transmitting portion 604-B. In some other embodiments,the material of the radiation transmitting portion 603-B may bedifferent from the material of the radiation transmitting portion 604-B.Note that the above embodiments are purely provided for illustration,the present disclosure is not limited to these embodiments. Personshaving ordinary skills in the art may make some variations, deformationsand/or modifications without any creativity according to the presentdisclosure. In some embodiments, the grids 603 and 604 may also beincorporated with some components such as electrodes. The variations,deformations and/or modifications are not departing from the spirits ofthe present disclosure.

The grids 603 and 604 may be controlled to move by the grid controller430 of the control module 220. The control factor may be a voltage, acurrent, an electric field, a magnetic field, or the like, or anycombination thereof. With the movement of the grids, the active area ofreceiving radiation for a detector cell of an X-ray detector may bechanged. For example, when the first grid 603 moves along theZ-direction when the position of the second grid 604 is fixed, theactive area of receiving the radiation on a detector cell along theZ-direction may be changed. For another example, when the second grid604 moves along the X-direction when the position of the first grid 603is fixed, the active area of receiving the radiation on a detector cellalong the X-direction may be changed. For another example, when thefirst grid 603 moves along the Z-direction and the second grid 604 movesalong the X-direction, the active area of receiving the radiation on adetector cell along the X-direction and Z-direction may both be changed.It should be not that, the above description about the movement of thegrids is merely an example, and not intend to be limiting. In someembodiments, the grid 603 and the grid 604 may move along a samedirection. The moving distance for the grid 603 and/or the grid 604 maybe arbitrary. In some embodiments, the grid 603 and the grid 604 maytilt about a certain axis, such as the x axis, y axis, or z axis. Thetilting of the first grid 603 and the second grid 604 may be about thesame or different directions. In some other embodiments, there may beonly one grid. The tilting and/or movement of the grid may still resultin changed active area of receiving radiation on a detector cell. Instill some other embodiments, there may be more than two grids. Thecombinational tilting and/or movement of each grid may also result inchanged active area of receiving radiation on a detector cell. When theactive area of receiving radiation on a detector cell is changed, thespecial resolution may be changed. The structure of the grids describedabove is aimed at a detector cell, but it should be noted that it mayalso be suitable for a whole detector or part of a whole detector.

It should be noted that the above description of the grids and relativemotions is merely provided for the purposes of illustration, and notintended to limit the scope of the present disclosure. For personshaving ordinary skills in the art, multiple variations and modificationsmay be made under the teachings of the present disclosure. In someembodiments, the grids may be within a same plane. In some embodiments,the grids may be arranged contacting directly with each other. Forexample, the grids may be arranged along the X-direction, theY-direction, or the Z-direction. In some embodiments, the grids may bespaced from each other by a certain distance. In some embodiments, agrid and a detector may attach to each other or be spaced from eachother by a certain distance. In some embodiments, the grids may bearranged parallel to a detector. In some embodiments, the grids may bearranged at an angle to the detector, and the angle may be adjustablefrom 0° to 360°. In some embodiments, the grids may be arranged inparallel with other grids or be arranged at angle to one or more othergrids, and the angle may be adjustable from 0° to 360°.

FIG. 7 shows a schematic sectional view of the effect of a flying focalspot on the active area of a detector cell. In the figure, the number701 and 702 may represent two positions of a focal spot of the radiationbeam inside an X-ray generating unit. The radiation emitted from thepoints 701 and 702 may project on a detector cell 704 through aradiation transmitting portion 703-B of a grid 703. It should be notedthat the structure showed in this figure is merely for the purposes ofdescribing conveniently, and is not intended to be limiting. For personshaving ordinary skills in the art, the number of the focal spot and thatof the grid may be varied arbitrarily according to some embodiments ofthe present disclosure, and the relative position of the two focal spotmay change according to some embodiments of the present disclosure.

As shown in FIG. 7, when the focal spot of the radiation beams is atpoint 701, the width of the region of receiving the radiation is S1.When the focal spot of the radiation beams moves to point 702 under thecontrol of, for example, the X-ray controller, the width of the regionof receiving the radiation is S2 that may be different from the widthS1. The difference in S1 and S2 may result in different active areasthat may receive the radiation on the detector cell 704. The point 702may be anywhere different from the point 701. In some embodiments, thepoint 702 may be on the left side of the point 701, on the right side ofthe point 701, above the point 701, under the point 701, or the like, ora combination thereof. For persons having ordinary skills in the art, itshould be understood that when the point 701 and the point 702 do notcoincide exactly, the width S1 and S2 may be different.

Beside, when the focal spot of the radiation beams is fixed, the changeof the location of the grid 703 may result in a different active area ona detector cell. In some embodiments, the grid 703 may move a distancetowards the focal spot 701 or the detector cell 704 according todifferent demands including, e.g., a desired spatial resolution, thesize of the X-ray imaging scanner, the whole size of the detector andthe size of a detector cell, or the like, or any combination thereof.There may be other factors that may influence the active area of adetector cell, such as, the width of the radiation transmitting portion703-B, the thickness of the radiation transmitting portion 703-B, theshape of the radiation transmitting portion 703-B, the distance betweenthe grid 703 and the detector cell 704, the distance between the focalspot of the radiation beam and the grid 703, the angle formed by thegrid 703 and the detector cell 704, the shape of the radiation beam, themotion speed of the focal spot and/or the grids, or the like, or anycombination thereof. In some embodiments, the shape of sectional view ofthe radiation transmitting portion 703-B may be trapezoid, taper,triangle, or other shapes such as a handstand T shape.

Those skilled in the art should understand that the above embodimentsare only utilized to describe the present disclosure. There are manymodifications and variations to the present disclosure without departingfrom the spirits of the present disclosure. For example, there may betwo or more grids arranged before the detector cell 704, and the activearea of a detector cell 704 may be determined by all the grids arranged.

FIG. 8 shows a schematic view of a combination of grids and a detector.The detector 803 may include a plurality of detector cells 802 supportedby a substrate 801. In some embodiments, a detector cell may include oneor more scintillator element and one or more photodetector element. Thescintillator element may include a material that may absorb ionizingradiation and/or emit a fraction of the absorbed energy in the form oflight. Any scintillator may include a material with at least one of thefollowing features including, for example, a high detective efficiency,high conversion efficiency, low absorption, a wide linear range, strongresistance to interference, or the like, or a combination thereof. Thephotodetector element in the present disclosure may be a photoelectricconversion element that may firstly detect an optical signal and thenconvert the optical signal into an electrical signal including, e.g., anelectrical current, an electrical voltage, and/or other electricalphenomena. In some embodiments, the thickness of the detector cell 802may be varied. The size of the detector cell 802 may be varied one ormore conditions including, for example, spatial resolution, sensitivity,stability, the size of the detector or the like, or any combinationthereof. The shape of the detector cell 802 may be circular, oval,rectangular, or the like, or any combination thereof. The detector cellmay be arranged regularly, or irregularly on the substrate 801. In someembodiments, the working conditions of each detector cell 802 may becontrolled independently by the control module 220.

The substrate 801 may be a solid substance providing a support for thedetector 803. The size of the substrate 801 may be varied according tothe size of the detector 803. The thickness of the substrate 801 may bevaried arbitrarily and not limited here. The overall shape of thesubstrate 801 may be planar, arc-shaped, or any other shaped substratein accordance to the different shapes of the X-ray detector 300. Eachpart of the substrate 801 may be circular, oval, rectangular, or thelike, or any combination thereof. The substrate 801 may be arrangedregularly, or irregularly. The substrate 801 may include, for example, asemiconducting material, an electrically insulating material, or thelike, or a combination thereof. In some embodiments, the semiconductingmaterial may include an elementary substance or a compound. Theelementary substance may include silicon, germanium, carbon, tin, or thelike. The compound may include silicon dioxide, silicon nitride, siliconcarbide, aluminum oxide, sapphire, germanium, gallium arsenide (GaAs),an alloy of silicon and germanium, indium phosphide (InP), poly(3-hexylthiophene), poly (p-phenylene vinylene), polyacetylene, or thelike, or their derivatives, or any combination thereof. In someembodiments, the insulating materials may include glass, porcelain,paper, polymers, plastics, or the like, or any combination thereof.Those skilled in the art should understand that the above embodimentsare only utilized to describe the present disclosure. There may be manymodifications and variations to the present disclosure without departingform the spirits of the present disclosure. For example, the substrateelement may be small chips to minimize the size of the X-ray detector.For another example, the X-ray detector may also be an assembly ofscintillator elements, photovoltaic conversion elements, chips and othercomponents. For still another example, the substrate or chip may beomitted in some embodiments. Similar modifications and variations arestill within the scope of the present disclosure described above.

As shown in FIG. 8, the first grid 603 and the second grid 604 may bearranged in front of the detector 803. The first grid 603 may beparallel to the second grid 604. The radiation transmitting portions603-B extending along the X-direction on the first grid 603 may beparallel with each other. The radiation transmitting portions 604-Bextending along the Z-direction on the second grid 604 may be parallelwith each other. It should be noted the above description about thegrids is merely an example, and not intended to limit the scope of thepresent disclosure. For persons having ordinary skills in the art,multiple variations and modifications may be made under the teachings ofthe present disclosure. In some embodiments, the shape of the radiationtransmitting portions 603-B and the radiation transmitting portions604-B may be regular, e.g., a rectangle, a trapezia, a parallelogram.The width and/or the length of the radiation transmitting portions 603-Band the radiation transmitting portions 604-B may be arbitrary. In someembodiments, the grid pitch of the radiation transmitting portions 603-Band the transmitting portions 604-B may be the same or different. Forthe first grid and/or the second grid, the grid pitches of the radiationtransmitting portions may be uniform, partially uniform, or non-uniform.For example, half of the radiation transmitting portions may have afirst grid pitch, and the remaining half of the radiation transmittingportions may have another grid pitch which may be different from thefirst grid pitch. For still another example, all the distances betweentwo neighbor radiation transmitting portions may be different. In someembodiments, the radiation transmitting portions 603-B may extend in thesame direction with the radiation transmitting portions 604-B. In someembodiments, the radiation transmitting portions 603-B may extend in adifferent direction with the radiation transmitting portions 604-B. Forexample, the extending direction of the radiation transmitting portions603-B and the extending direction of the radiation transmitting portions604-B may be orthogonal. The modifications and variations are stillwithin the scope of the present disclosure described above. In someembodiments, a detector cell may correspond to one or more radiationtransmitting portion(s) from a grid. In some embodiments, a detectorcell may correspond to one or more radiation transmitting portion(s)from more than one grids.

The grid 603 and grid 604 may be controlled to move by the gridcontroller 430 in the control module 220. The control factor may be avoltage, a current, an electric field, a magnetic field, or the like, orany combination thereof.

FIG. 9 is a schematic view of active areas of detector cells on adetector. It should be noted that the arrangement of the detector cellsis merely for illustration purposes, and is not intended to be limiting.In some embodiments, the gaps among the detector cells may be filledwith some materials to absorbed and/or block the X-rays to prevent thechips from being influenced.

As illustrated in the figure, each detector cell 802 may have an activearea 901, which may be adjustable according to some considerationsincluding, e.g., the spatial resolution, the system noise, one or moreother types of noises, or the like, or a combination thereof. The activearea 901 may be determined by, for example, the geometrical relationshipof the focal spot of the radiation beam and/or the grids between thetarget and the detector. The position of the active area 901 may moveand/or the scale of the active area 901 may change when the focal spotof the radiation beam moves, and/or the position of the grids changes.

It should be noted that the above description of the active area ismerely provided for the purposes of illustration, and not intended tolimit the scope of the present disclosure. For persons having ordinaryskills in the art, multiple variations and modifications may be madeunder the teachings of the present disclosure. For example, the shape ofthe active area may be a triangle, quadrangle, including, a rectangle, adiamond, or any shapes with four edges. In some embodiments, the shapeformed by these positions may be a circular, an ellipse. In someembodiments, the shape of the active area may be an irregular shape. Insome embodiments, there may be several active areas for one detectorcell and the active areas may have a same, or different, shape(s). Forexample, there may be two or more rectangular active areas for adetector cell. In some embodiments, the position of the active areas maybe anywhere of a detector cell.

FIG. 10-A and FIG. 10-B are schematic diagrams showing an exemplaryarrangement of the grid and the detector cell according to someembodiments of the present disclosure. To be convenient for description,only one detector cell and one grid used for adjusting the active areaof the detector cell are shown in FIG. 10-A. It should be noted that adetector including a plurality of detector cells may be used foracquiring X-ray signals (see FIG. 8). And it should be noted that atleast one grid may be used for adjusting the active area of the detectorcells (e.g., two grids may be used, see FIG. 8). As illustrated in FIG.8, a grid may include one or more radiation transmitting portions 603-B(or 604-B) and one or more radiation absorbing portions 603-A (or604-A). X-rays may be transmitted through the radiation transmittingportions while absorbed by the radiation absorbing portions. Theradiation transmitting portion may be an empty gap, or may be filledwith certain medium. Exemplary medium may include inorganic material,organic material, or the like, or any combination thereof. Exemplaryinorganic material may include silicon, carbon fiber, glass, or thelike, or a combination thereof. Exemplary organic material may includeplastic, rubber, or the like, or a combination thereof.

A radiation transmitting portion, or referred to as a radiationtransmitting section, may be used for adjusting the active area of adetector cell. The active area of a detector cell may receive radiationfrom a radiation source that passes through at least one of a pluralityof radiation transmitting sections of a grid. At least one of theradiation transmitting section may include at least one transmittingpart located above a detector cell. The active area may correspond tothe radiation transmitting section or portion in a grid located abovethe detector cell. The dimension of the active area of a detector cellmay be comparable to the dimension of the detector cell. For example,assume the dimension of the detector cell is 1×1 mm², the dimension ofthe active area corresponding to the transmitting part located above thedetector cell may be less than 1 mm², such as, from 9/10 mm² to 1 mm²,or from ⅘ mm² to 9/10 mm², or from ¾ mm² to ⅘ mm², or from ½ mm² to ¾mm², or from ⅖ mm² to ½ mm², or from ⅓ mm² to ⅓ mm², or from ¼ mm² to ⅓mm², or from ⅕ mm² to ¼ mm², or from ⅙ mm² to ⅕ mm², or below ⅙ mm², orthe like. In some embodiments, the dimension of the detector cell may beP mm² other than 1×1 mm², and the dimension of the active areacorresponding to the transmitting part located above the detector cellmay be b*P. The value of the factor b may be any number in the range (x,1), such as ½, ⅓, ¼, ⅕, ⅙, 1/10, 1/20, 1/50, 1/100, or the like. As usedherein, the variable x may be set by the system according to a defaultsetting, or may be set by an operator, or may be set according torequirements of signal acquisition process. The value of x may bebetween 0 and 1. In some embodiments, the variable x may be set to beequal to or greater than 0.01, or 0.05, or 0.1, or 0.2, or 0.3, or 0.4,or 0.5, or 0.6, or 0.7, or 0.8.

Merely by way of example, the radiation transmitting portions may bearranged along X-direction or along Z-direction to form a stripe pattern(e.g., the shape of the radiation transmitting portion is rectangle). Insome embodiments, the shape of the radiation transmitting portion may besquare, triangle, circle, oval, polygon, irregular shape, or the like,or a combination thereof. The area ratio of the radiation transmittingportions and the radiation absorbing portions may be a fixed value, ormay be adjustable under different conditions. Similarly, the gridpitches among the radiation transmitting portions may be a fixed value,or may be adjustable under different conditions. Merely by way ofexample, a doctor or an operator other than the doctor (e.g., ahealth-care worker) may manually adjust the grid pitches according torequirements of signal acquisition process or according to requirementsof image quality (e.g., resolution, S/N (signal/noise), amplificationfactor, or the like, or a combination thereof.). For another example,the operator may adjust the grid pitches based on instructions inputtedby the doctor or a related operator, or based on system default, orbased on options regarding preset parameters (e.g., different conditionscorrespond to different parameters). The preset parameters may includesignal acquisition speed, size of detector pixel, emitting voltage,emitting current, temperature, or the like, or a combination thereof.

FIG. 10-A provides one example regarding the adjusting of active area ofa detector cell according to some embodiments of the present disclosure.A top view and a side view from Z-direction are shown. As illustrated,the region filled with slash lines represents the radiation absorbingportions of the grid, the region filled with points represents atransmitting part of a radiation transmitting portion of the grid, andthe region with no fill represents the detector cell. In this example,the shape of the transmitting part of the radiation transmittingportions may be rectangle as illustrated in FIG. 10-A. During an X-rayimage acquisition process, based the system default or instructionsinputted by an operator, the grid may be controlled to move toward thedetector cell or the focal spot. The controlling may be performed by thecontrol module 220, or may be performed by the grid controller 430, ormay be performed by any module or unit integrated in the system that maybe configured for controlling positions or arrangements of components ofthe system. For purposes to be illustrative, a radiation transmittingportion or a transmitting part of a radiation transmitting portion maybe arranged on the middle part of the detector cell, but it should benoted that this illustration will not limit the scope of the presentdisclosure. It may be seen from the top view and the side view that dueto the existence of the radiation transmitting portion and the radiationabsorbing portion of the grid, the active area of the detector cell isreduced. The active area of the detector cell may be adjusted byadjusting the radiation transmitting portion's shape, size, position,arrangement, or the like, or a combination thereof.

The description of the arrangements of the grid and the detector cellare intended to be illustrative, and not to limit the scope of thepresent disclosure. Many alternatives, modifications, and variationswill be apparent to those skilled in the art. The features, structures,methods, and other characteristics of the exemplary embodimentsdescribed herein may be combined in various ways to obtain additionaland/or alternative exemplary embodiments. For example, other than thesituation illustrated in FIG. 10-A, the size or shape of the radiationtransmitting portion may be changed, thus the active area of thedetector cell or the size of the transmitting part of the radiationtransmitting portion may be accordingly reduced. In some embodiments,assume that the size of a detector cell illustrated in FIG. 10-A is Smm², the size of the radiation transmitting portion or the size of thetransmitting part of the radiation transmitting portion may be reducedto a*S mm² according to the requirements of signal acquisition process.The value of the factor a may be any number in the range of (0, 1)(e.g., ½, ⅓, ¼, ⅕, ⅙, 1/10, 1/20, 1/50, 1/100, etc.). Similarly the sizeof the radiation transmitting portion or the transmitting part of theradiation transmitting portion may be enlarged accordingly.

FIG. 10-B provides another example regarding the adjusting of the activearea of the detector cell according to some embodiments of the presentdisclosure. It may be seen from the top view that two transmitting parts1002 of the radiation transmitting portion of the grid are arrangedabove the detector cell. Similarly the active area of the detector cellis reduced due to the existence of the radiation transmitting portionand the radiation absorbing portion. Referring back to FIG. 10-A, theactive area of the detector cell may be adjusted or may be controlled byadjusting one or more parameters of the radiation transmitting portions.The parameters may include the shape, the size, the grid pitch among theradiation transmitting portions, the amount of the radiationtransmitting portions, the position of the grid, the filling material ofthe radiation transmitting portions, or the like, or a combinationthereof. As shown in FIG. 10-B, two transmitting parts of the radiationtransmitting portions are arranged, it should be noted that thearrangement is only for purpose of illustration, and not intended tolimit the scope of the present disclosure. Many alternatives,modifications, and variations will be apparent to those skilled in theart. The features, structures, methods, and other characteristics of theexemplary embodiments described herein may be combined in various waysto obtain additional and/or alternative exemplary embodiments. Forexample, other than the two exemplary arrangements, one, three or moretransmitting parts of the radiation transmitting portions may bearranged above the detector cell. Thus the active area of the detectorcell may be adjusted accurately and continuously.

FIG. 11-A and FIG. 11-B are schematic diagrams showing another exemplaryarrangement of the grid and the detector cell according to someembodiments of the present disclosure. Two grids are arranged above thedetector array used for adjusting the active areas of the detectorcells. To be convenient for illustration, only one detector cell isshown. According to this embodiment, two grids may be configured foradjusting the active areas of the detector cells illustrated in FIG. 8.In some embodiments, the two girds may be configured orthogonally, ormay be arranged at a certain angle with each other. The angle may be10°, 15°, 30°, 45°, 60°, or the like. The active area of the detectorcell may be adjusted based on the change of the angle. The change of theangle may be performed based on system default, or may be based oninstructions inputted by a doctor or an operator other than the doctor,or may be based on instructions or preset conditions loaded from theserver. The change of the angle may be performed by the control module220, or may be performed by the grid controller 430, or may be performedby any module or unit integrated in the system that may be used forcontrolling positions or arrangements of components of the system. Thetype of the two grids may be the same or may be different.

FIG. 11-A provides one example regarding the adjustment of the activearea of a detector cell according to some embodiments of the presentdisclosure. A top view, a side view from X-direction, and a side viewfrom the Z-direction are shown. In this example, it may be seen from thetop view that a “+” radiation transmitting region is generated by twoorthometric grids. In some embodiments, the two grids may be arranged ata certain angle, and thus the radiation overlapping area may be adjustedby tilting one or both grids. The size of the “+” radiation transmittingregion may be changed by changing the size or the shape of the radiationtransmitting portions of the two grids. Thus the active pixels in theX-direction, the Z-direction, and the XY-plane may be adjusted andcontrolled. It should be noted that the active area may be determined byboth the radiation transmitting regions of the grid(s) and the positionof the focal spot.

FIG. 11-B provides another example regarding the adjusting of activearea of a detector cell according to some embodiments of the presentdisclosure. Similarly, a top view, a side view from the X-direction, anda side view from the X-direction are shown. In this example, a radiationtransmitting region illustrated in FIG. 11-B is generated by twoorthometric grids. Name the upper gird as the first grid and name theunder grid as the second gird (see FIG. 8). In the example, the gridpitches among the radiation transmitting portions of the two grids maybe different. It may be seen from the side view from the X-directionthat one radiation transmitting portion of the first grid is arrangedabove the detector cell, and no radiation transmitting portion of thesecond grid is arranged on the detector cell. It may be seen from theside view from the Z-direction that two radiation transmitting portionsof the second grid are arranged above the detector cell, and noradiation transmitting portion of the first grid is arranged on thedetector cell. This description is only for purpose of illustration,more than one radiation transmitting portions of the first grid andother than two radiation transmitting portions of the second grid may bearranged above the detector cell. The radiation transmitting region ofthe detector cell may be adjusted and controlled by the two grids underdifferent conditions.

FIG. 12 is a schematic diagram showing another exemplary arrangement ofthe grid and the detector cell according to some embodiments of thepresent disclosure. As illustrated, the radiation transmitting portionof the grid is arranged on the edge of the detector cell. Similar to thesituation that the radiation transmitting portion of the grid arrangedin the middle of the detector cell, the active area of the detector cellmay be reduced by the existence of the grid. For example, ½ of thetransmitting part of the radiation transmitting portion of the grid islocated above the detector cell, the active area of the detector cell isreduced as ½ of the area of the transmitting part of the radiationtransmitting portion. In a further example, the grid may be caused tomove along the X-direction or along the Z-direction, while approachingthe edge of detector cell, the radiation transmitting region above thedetector cell may vary in real time. According to desired image qualityor signal acquisition requirements of different organs of the object,the gird may be controlled to move under a certain speed or along acertain route. In still a further example, there may be two or moregrids. The grids may be controlled together or may be controlledindependently. The moving of the grids may include translation, tilt, orthe like, or a combination thereof. The adjusting of the active area ofa detector cell may be in real time, or may be pre-set before the X-rayimage acquisition process commences, or may be performed when needed.

The description of the arrangements of the grid and the detector cellare intended to be illustrative, and not to limit the scope of thepresent disclosure. Many alternatives, modifications, and variationswill be apparent to those skilled in the art. The features, structures,methods, and other characteristics of the exemplary embodimentsdescribed herein may be combined in various ways to obtain additionaland/or alternative exemplary embodiments. For example, parametersregarding the adjusting of the active area of a detector cell may becontrolled in real time and may be controlled independently. Theparameters may include but not limited to, the size or shape of theradiation transmitting portion, the moving speed of the grids, thenumber of the grids, the angle between the grids, or the like, or acombination thereof.

FIG. 13-A and FIG. 13-B are schematic diagrams showing exemplaryarrangements of a grid, a shielding device, and a detector cellaccording to some embodiments of the present disclosure. For simplicity,only a portion of a grid, a part of a shielding device, and a detectorcell are shown in FIG. 13-A and FIG. 13-B. It is for illustrationpurposes and not intended to limit the scope of the present disclosure.It is understood that an imaging system may include more than one grids,that a grid may include more than one shielding device, and that animaging system may include more than one detector cells.

In FIG. 13-A, a top view from the Y-direction is shown. A plate of theshielding device 1302 may be placed on or above the grid 1301. In someembodiments, the shielding device 1302 and the grid 1301 may physicallycontact or be in direct contact with each other. In some embodiments,the shielding device 1302 and the grid 1301 may be spaced apart fromeach other by a distance. In some embodiments, the plate of theshielding device 1302 may contact the radiation absorbing portion 1301-Aof the grid 1301. In some embodiments, the plate of the shielding device1302 may contact the radiation transmitting portion 1301-B of the grid1301. In some embodiments, the shielding device 1302, or a portionthereof, may be parallel to the grid 1301. In some embodiments, theshielding device 1302, or a portion thereof, may be placed at an angleof inclination with respect to the grid 1301. The angle may beadjustable from 0° to 360°.

In FIG. 13-B, the radiation absorbing portion 1301-A may be filled withmaterials including gas, therefore, the shielding device 1302 may beplace on a side of the radiation absorbing portion 1301-A of the grid1301 as shown in FIG. 13-B. It should be noted that the position of theshielding device shown in the figure is merely an exemplary example, andnot intend to be limiting. In some embodiments, the shielding device1302 may be any position in the radiation absorbing portion 1301-A. Insome embodiments, the shielding device 1302 may be placed apart from thegrid with a distance. For the purposes of describing conveniently, FIG.13-B may show an exemplary example.

In FIG. 13-B, a side view from Z-direction of the arrangement is shown.A plate of the shielding device 1302 is illustrated in FIG. 13-B. Theplate of the shielding device 1302 may be movably attached to a side ofthe radiation absorbing portion 1301-A at a connecting point 1304. Theplate of the shielding device 1302 may swing around the connecting point1304 by any angle between, for example, 0° to 90°, or 0° to 180°, or 0°to 270°. The trajectory of one end of the plate in the shielding device1305 may form an arc with a radius. When the plate of the shieldingdevice 1305 is at different positions, the active area of the detectorcell 1303 may be different. The different length or width of the plateof the shielding device 1305 (the radius shown in FIG. 13-B) may alsoresult in different active area of the detector cell 1303.

The shape of the shielding device 1302 may be regular or irregular.Merely by way of example, the shielding device 1302 may be one or moreplates with dimensions including, for example, a length, a width, aheight, etc. The length and the width of a plate of the shielding device1302 may be comparable to a radiation transmission section portion1301-B of the grid 1301.

The working condition or a position of the shielding device 1302, or aportion there of (for example, a plate of the shielding device 1302) mayinclude an extended position, a partially extended position, and acontracted position. As used herein, an extended position of theshielding device 1302, or a portion there of, may be one at which theshielding device 1302, or a portion thereof, completely blocks orabsorbs one or more radiation transmission section portions 1301-B ofthe grid 1301, and no area(s) of one or more radiation transmissionsection portions 1301-B of the grid 1301 may be available for passage ofradiation. As used herein, a partially extended position of theshielding device 1302, or a portion there of, may be one at which theshielding device 1302, or a portion thereof, partially blocks one ormore radiation transmission section portions 1301-B of the grid 1301,and partial area(s) of one or more radiation transmission sectionportions 1301-B of the grid 1301 may be available for passage ofradiation. As used herein, a contracted position of the shielding device1302, or a portion there of, may be one at which the shielding device1302, or a portion thereof, does not block any part of one or moreradiation transmission section portions 1301-B of the grid 1301, and theentire area(s) of one or more radiation transmission section portions1301-B of the grid 1301 may be available for passage of radiation. Theblocking of radiation by the shielding device 1302 or a portion thereofmay be achieved by reflection or absorption.

The working conditions of the shielding device 1302 may include theposition relative to the detector cell or the grid 1301, the anglerelative to the detector cell or the grid 1301, the motion speed of theshielding device 1302 or a portion thereof, the motion direction of theshielding device 1302 or a portion thereof, or the like, or anycombination thereof. In some embodiments, the movement of the shieldingdevice 1302 may include a motion along a certain direction, e.g., theX-direction, the Y-direction, or the Z-direction. In some embodiments,the shielding device 1302 may tilt with respect to a certain axis orwith respect to the grid 1301. When the whole or part of the shieldingdevice 1302 is above the radiation transmitting portion 1301-B of thegrid 1301, the shielding device or a portion thereof is in its extendedposition or partially extended position, and the radiation blocked orabsorbed by the shielding device 1302 may cause a change of therespective active area of the detector cell.

The control module 220 in the system may control the working conditionor position of the shielding device 1302, or a portion thereof (forexample, one or more plates of the shielding device 1302 as illustratedin FIG. 13-A and FIG. 13-B), to adjust the active area of a detectorcell, or the part of the radiation transmission portion 1301-B of thegrid 1301 that may be available for passage of radiation. The controlmay be achieved by controlling a voltage, a current, an electric field,a magnetic field, or the like, or any combination thereof, that may beused to adjust the working condition or position of the shielding device1302, or a portion thereof.

It should be noted that the above description about the shielding deviceis merely an example, and not intended to limit the scope of the presentdisclosure. For persons having ordinary skills in the art, variousvariations and modifications may be conducted under the teaching of thepresent disclosure. However, those variations and modifications may notdepart from the protecting of the present disclosure. Exemplaryvariations may include that each grid may be equipped with one or moreshielding devices, that multiple shield devices of a grid may be thesame or different shielding devices, and that the dimensions of theshielding device of one grid may be the same as or different from thatof another grid. The change of the working condition of the shieldingdevice of one grid by way of the motion of the shielding devices or aportion thereof may be synchronized with or different from that of thesecond grid. The synchronization of the motion of two shielding devicesor a portion thereof may include one or more characteristics including,for example, uniform rate or speed of the motion, uniform direction ofthe motion, uniform timing of the motion, or the like, or a combinationthereof. For another example, the dimensions of the part of theshielding device in each transmitting portion of one grid may be thesame or different. The change of the state of the shielding device ineach transmitting portion of one grid may be the same or different. Forinstance, the shielding device relating to one grid may tilt withrespect to an axis by a first angle, and the shielding device relatingto another grid may tilt with respect to another axis by a second angle.As used herein, the first angle may be the same as or different from thesecond angle.

Having thus described the basic concepts, it may be rather apparent tothose skilled in the art after reading this detailed disclosure that theforegoing detailed disclosure is intended to be presented by way ofexample only and is not limiting. Various alterations, improvements, andmodifications may occur and are intended to those skilled in the art,though not expressly stated herein. These alterations, improvements, andmodifications are intended to be suggested by this disclosure, and arewithin the spirits and scope of the exemplary embodiments of thisdisclosure.

Moreover, certain terminology has been used to describe embodiments ofthe present disclosure. For example, the terms “one embodiment,” “anembodiment,” and/or “some embodiments” mean that a particular feature,structure or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure.Therefore, it is emphasized and should be appreciated that two or morereferences to “an embodiment” or “one embodiment” or “an alternativeembodiment” in various portions of this specification are notnecessarily all referring to the same embodiment. Furthermore, theparticular features, structures or characteristics may be combined assuitable in one or more embodiments of the present disclosure.

Further, it will be appreciated by one skilled in the art, aspects ofthe present disclosure may be illustrated and described herein in any ofa number of patentable classes or context including any new and usefulprocess, machine, manufacture, or composition of matter, or any new anduseful improvement thereof. Accordingly, aspects of the presentdisclosure may be implemented entirely hardware, entirely software(including firmware, resident software, micro-code, etc.) or combiningsoftware and hardware implementation that may all generally be referredto herein as a “block,” “module,” “engine,” “unit,” “component,” or“system.” Furthermore, aspects of the present disclosure may take theform of a computer program product embodied in one or more computerreadable media having computer readable program code embodied thereon.

Similarly, it should be appreciated that in the foregoing description ofembodiments of the present disclosure, various features are sometimesgrouped together in a single embodiment, figure, or description thereoffor the purpose of streamlining the disclosure aiding in theunderstanding of one or more of the various inventive embodiments. Thismethod of disclosure, however, is not to be interpreted as reflecting anintention that the claimed subject matter requires more features thanare expressly recited in each claim. Rather, inventive embodiments liein less than all features of a single foregoing disclosed embodiment.

1. A system comprising: a radiation source; a detector comprising aplurality of detector cells; and a first grid located between theradiation source and the detector cells, the first grid comprising aplurality of radiation transmitting sections, at least one of theplurality of detector cells comprising an active area receivingradiation from the radiation source that passes through at least one ofthe plurality of radiation transmitting sections of the first grid, theactive area being adjustable by adjusting the first grid, and theradiation source, the first grid, and the detector cells beingoperatively coupled for detecting an object.
 2. The system according toclaim 1, the adjusting the first grid comprising adjusting the positionof the first grid or tilting the first grid by an angle.
 3. The systemaccording to claim 1, further comprising a shielding device configuredfor adjustably blocking the radiation source.
 4. The system according toclaim 1, further comprising a second grid, the second grid being locatedbetween the first grid and the detector.
 5. The system according toclaim 4, the second grid comprising a plurality of radiationtransmitting portions, and at least one of the plurality of radiationtransmitting portions being coupled with the active area.
 6. The systemaccording to claim 5, the first grid and the second grid being moveablerelative to each other.
 7. The system according to claim 5, the activearea being at least partially determined by the at least one of theplurality of radiation transmitting sections of the first grid and atleast one of the plurality of radiation transmitting portions of thesecond grid.
 8. The system according to claim 4, at least one of theplurality of radiation transmitting sections extending in a firstdirection.
 9. The system according to claim 8, the first grid beingmoveable in a second direction perpendicular to the first direction. 10.The system according to claim 8, the second grid being moveable in thefirst direction.
 11. The system according to claim 1, the radiationsource comprising a plurality of focal spots.
 12. The system accordingto claim 11, the detecting the object comprising scanning the objectwith radiation from at least two different focal spots of the radiationsource.
 13. A method comprising: locating a first grid between aradiation source and a detector, the detector comprising a plurality ofdetector cells, the first grid comprising a plurality of radiationtransmitting sections; emitting radiation from the radiation sourcetoward the first grid; and receiving, on an active area of at least oneof the plurality of detector cells, the radiation that passes through atleast one of the plurality of radiation transmitting sections of thefirst grid, the active area being adjustable by adjusting the firstgrid, the radiation source, the first grid, and the detector cells beingoperatively coupled for detecting an object.
 14. The method according toclaim 13, the adjusting the first grid comprising adjusting the positionof the first grid, or tilting the first grid by an angle.
 15. (canceled)16. The method according to claim 13, further comprising locating asecond grid between the first grid and the detector.
 17. The methodaccording to claim 16, the second grid comprising a plurality ofradiation transmitting portions, and at least one of the plurality ofradiation transmitting portions being coupled with the active area,wherein the active area is at least partially determined by the at leastone of the plurality of radiation transmitting sections of the firstgrid and the at least one of the plurality of radiation transmittingportions of the second grid.
 18. The method according to claim 17, thefirst grid and the second grid being moveable relative to each other.19. (canceled)
 20. The method according to claim 13, the at least one ofthe plurality of radiation transmitting sections extending in a firstdirection.
 21. The method according to claim 20, further comprisingmoving the first grid in a second direction perpendicular to the firstdirection.
 22. The method according to claim 20, further comprisingmoving the second grid in the first direction.
 23. (canceled) 24.(canceled)